In general, piezoelectric materials are ABO3 perovskite type metal oxides, such as lead zirconate titanate (hereinafter referred to as “PZT”). However, PZT contains lead as an A site element, and its effect on the environment is regarded as a problem. Thus, there is a demand for piezoelectric materials of lead-free perovskite type metal oxides.
One known piezoelectric material of a lead-free perovskite type metal oxide is barium titanate. In order to improve the characteristics of barium titanate, materials based on barium titanate are being developed.
PTL 1 discloses a piezoelectric material containing barium titanate, wherein the A site of the barium titanate is partly substituted by Ca. PTL 2 discloses a material containing the piezoelectric material and Mn, Fe, or Cu, wherein the A site of the barium titanate is partly substituted by Ca. These materials have a higher mechanical quality factor than barium titanate but disadvantageously have a poor piezoelectric property.